Our objectives are to investigate basic aspects of brain tumors (especially gliomas) in etiological, immunological, tumor biological, and experimental chemotherapeutic areas. In etiological studies we will seek the association of retroviruses and human papovaviruses with spontaneous human or animal gliomas; establish the transplacental neuro-oncogenicity of acrylonitrile; study genetic susceptibility of mice to neuro-oncogenetic viruses and chemical carcinogens; and use banding and non-banding cytogenetic techniques to guide etiological studies of animal and human gliomas. In immunological studies, we will purify and characterize antigens associated with spontaneous human and mouse gliomas, and determine if quantitation of these antigens can be used to monitor tumor size, and as an adjunct in diagnosis. In tumor biological studies, we will establish whether or not the phenotypic heterogeneity of neoplastic cells in human gliomas with respect to morphological, biochemical, and immunological differentiation extends to chemotherapeutic sensitivity, as tested in athymic mice; and whether endothelial cells of human and experimental gliomas are neoplastic. We will develop and use a glioma animal model in gerbils to test intracarotid chemotherapy; and we will develop reliable animal models of medulloblastoma and craniopharyngioma in athymic mice.